Information Retrieval Apparatus

1. An information retrieval apparatus for retrieving information, stored in a database, based on a search request, said information retrieval apparatus comprising: a general association dictionary storage unit that stores information identifying a relationship between words included in the information stored in the database; a preference-based association dictionary storage unit that stores information identifying a relationship, between the words included in the information stored in the database, which reflects a user's preferences regarding the information stored in the database, the information identifying the relationship that is stored in said preference-based association dictionary storage unit being independent from the information identifying the relationship that is stored in said general association dictionary storage unit; a matching degree calculation unit that extracts, based on (i) preference-based association dictionary characteristic information indicating a characteristic of a word stored in said preference-based association dictionary storage unit, (ii) status information indicating the user's status and (iii) emotion information expressing an emotion of the user, a word from information input by the user that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion information, and that calculates, as a degree of matching, a value calculated based on a weigh value of the extracted word; a search condition generation unit that: selects said general association dictionary storage unit when the degree of matching is equal to or smaller than a predetermined threshold value, and selects said preference-based association dictionary storage unit when the degree of matching is greater than the predetermined threshold value; obtains, as one or more related words, and depending on a number indicated by the value calculated as the degree of matching, one or more words that relate to the information input by the user, the one or more related words being obtained from one of said general association dictionary storage unit and said preference-based association dictionary storage unit that is selected by said search condition generation unit; and generates a search condition using the obtained one or more related words; and a retrieval unit that retrieves, from the database, information which meets the search condition generated by said search condition generation unit.

2. The information retrieval apparatus according to claim 1 , wherein said matching degree calculation unit uses, as the preference-based association dictionary characteristic information, a profile that contains information relating to the user's preferences.

3. The information retrieval apparatus according to claim 2 , wherein said preference-based association dictionary storage unit stores, as a profile reflecting the user's preferences regarding the information stored in the database, a situation keyword indicating a usage status of the user and an emotion keyword expressing an emotion of the user, and wherein said matching degree calculation unit calculates a degree of matching between the information input by the user and the information identified in the profile of the user, the information input by the user being the situation keyword and the information identified in the profile being the emotion keyword expressing the emotion of the user.

4. The information retrieval apparatus according to claim 1 , wherein said matching degree calculation unit uses, as the preference based association dictionary characteristic information, a word stored in said preference-based association dictionary storage unit.

5. The information retrieval apparatus according to claim 1 , wherein said matching degree calculation unit uses, as the information input by the user, information previously retrieved by said retrieval unit.

6. The information retrieval apparatus according to claim 1 , wherein said search condition generation unit obtains the one or more related words depending on a number indicated by the value calculated as the degree of matching, the one or more related words being obtained from said preference-based association dictionary storage unit and said general association dictionary storage unit.

7. The information retrieval apparatus according to claim 1 , further comprising: a display unit that displays the one or more related words; and a related word selection input unit that retrieves at least one related word selected by the user from among the one or more related words displayed by said display unit, wherein said search condition generation unit displays the related word obtained from the one of said general association dictionary storage unit and said preference-based association dictionary storage unit, and wherein said search condition generating unit generates a search condition using the related word retrieved by said related word selection input unit when at least one related word is selected by the user from among the related words displayed on said display unit.

8. The information retrieval apparatus according to claim 1 , wherein said matching degree calculation unit performs the extraction of the word from the information input by the user that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion information, based on the preference-based association dictionary characteristic information indicating the characteristic of a word stored in said preference-based association dictionary storage unit, and at least one of (a) the status information indicating the user's status and (b) the emotion information expressing the emotion of the user, and wherein said matching degree calculation unit calculates, as the degree of matching, the value calculated based on the weight value of the extracted word.

9. A program information retrieval apparatus for retrieving program information, stored in a database, based on a search request, said program information retrieval apparatus comprising: a general association dictionary storage unit that stores information identifying a relationship between words included in the program information stored in the database; a preference-based association dictionary storage unit that stores information identifying a relationship, between the words included in the program information stored in the database, which reflects a user's preferences regarding the program information stored in the database, the information identifying the relationship that is stored in said preference-based association dictionary storage unit being independent from the information identifying the relationship that is stored in said general association dictionary storage unit; a matching degree calculation unit that extracts, based on (i) preference-based association dictionary characteristic information indicating a characteristic of a word stored in said preference-based association dictionary storage unit, (ii) status information indicating the user's status and (iii) emotion information expressing an emotion of the user, a word from information input by the user that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion information, and that calculates, as a degree of matching, a value calculated based on a weight value of the extracted word; a search condition generation unit that: selects said general association dictionary storage unit when the degree of matching is equal to or smaller than a predetermined threshold value, and selects said preference-based association dictionary storage unit when the degree of matching is greater than the predetermined threshold value; obtains, as one or more related words, and depending on a number indicated by the value calculated as the degree of matching, one or more words that relate to the information input by the user, the one or more related words being obtained from one of said general association dictionary storage unit and said preference-based association dictionary storage unit that is selected by said search condition generation unit; and generates a search condition using the obtained one or more related words; and a retrieval unit that retrieves, from the database, program information which meets the search condition generated by said search condition generation unit.

10. An information retrieval method of using an apparatus to retrieve information, stored in a database, based on a search request, wherein the apparatus includes (i) a general association dictionary storage unit that stores information identifying a relationship between words included in the information stored in the database, and (ii) a preference-based association dictionary storage unit that stores information identifying a relationship, between the words included in the information stored in the database, which reflects a user's preferences regarding the information stored in the database, the information identifying the relationship that is stored in the preference-based association dictionary storage unit being independent from the information identifying the relationship that is stored in the general association dictionary storage unit, and wherein said information retrieval method comprises: extracting, based on (i) preference-based association dictionary characteristic information indicating a characteristic of a word stored in a preference-based association dictionary storage unit, (ii) status information indicating the user's status, and (iii) emotion information expressing an emotion of the user, a word from information input by the user that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion; calculating, using a calculation unit, as a degree of matching, a value based on weight value of the extracted word; selecting the general association dictionary storage unit when the degree of matching is equal to or smaller than a predetermined threshold value, and the preference-based association dictionary storage unit when the degree of matching is greater than the predetermined threshold value; obtaining, as one or more related words, and depending on a number indicated by the value calculated as the degree of matching, one or more words that relate to the information input by the user, the one or more related words being obtained from one of the general association dictionary storage unit and the preference-based association dictionary storage unit that is selected by said selecting; generating a search condition using the obtained one or more related words; and retrieving, from the database, information which meets the search condition generated in said generating of the search condition.

11. A computer-readable storage medium having a program stored thereon, the program for being executed on an apparatus for retrieving information, stored in a database, based on a search request, the apparatus including (i) a general association dictionary storage unit that stores information identifying a relationship between words included in the information stored in the database, and (ii) a preference-based association dictionary storage unit that stores information identifying a relationship, between the words included in the information stored in the database, which reflects a user's preferences regarding the information stored in the database, the information identifying the relationship that is stored in the preference-based association dictionary storage unit being independent from the information identifying the relationship that is stored in the general association dictionary storage unit, and the program causing a computer to execute a method comprising: extracting, based on (i) preference-based association dictionary characteristic information indicating a characteristic of a word stored in a preference-based association dictionary storage unit, (ii) status information indicating the user's status, and (iii) emotion information expressing an emotion of the user, a word that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion information; calculating, using a calculating unit, as a degree of matching, a value based on a weight value of the extracted word; selecting the general association dictionary storage unit when the degree of matching is equal to or smaller than a predetermined threshold value, and the preference-based association dictionary storage unit when the degree of matching is greater than the predetermined threshold value; obtaining, as one or more related words, and depending on a number indicated by the value calculated as the degree of matching, one or more words that relate to the information input by the user, the one or more related words being obtained from one of the general association dictionary storage unit and the preference-based association dictionary storage unit that is selected by said selecting; generating a search condition using the obtained one or more related words; and retrieving, from the database, information which meets the search condition generated in said generating of the search condition.